When Tunisia revolted the world was shocked because it was so unexpected. When Egypt arose the world stood back because, while Mubarak was an asshole, he was our asshole.
He is using tanks to attack under-armed rebels and bombing helpless civilians from the air. All the while the United Nations, Arab League, African Union, and the United States wring their hands and do nothing.
The excuse, of course, is the same as Pol Pot's devastation of Cambodia and the Hutu genocide in Rwanda - the suffering of others is none of our business. Add in the fact that the world only values what lies beneath the sands of Libya (oil) and that the nations of the world believe the flesh living above ground is worthless.
I would be remiss if I didn't point out that the Pentagon has a purely selfish reason for seeing the Libyan Civil War play out without interruption. They are using similar tactics (tanks and aerial attacks) in Afghanistan and they are hoping to pick up a few tips from how Gadhafi's forces do things.